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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1918832c9e33b976f02dc5404ba706a3c9ea08c4f44c902c796f9e327113aec0' 
  AND token = 'kl1OnzqEGiTuhpJU9KeqBdQHnNfe+dxkzOpptfThnjQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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