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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '43917de0a6fe3a3b14f8a47b1b8624e6e0ab35185ca3d5b8159eb7b2b6dc8518' 
  AND token = 'PHH+PF/+9YpvAAaHFRjJxEtgMjEpMTKnIKvroe/NA2g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}