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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c69cf7b0cf8c101546b09e80713cb09d39c94539f68da26fce0b02db6b34f2a2' 
  AND token = '3O7s3XBE4WySL0Ufxns3Q73mV/Ymj9Fl2MneN42rBEg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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