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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'fb2b198cc4257d3c457cd43f0ae40c3c45f5af7e22665e5023cbd26d39cda316' 
  AND token = 'ph8vkey78cJYw4EHub4RkMjPifOCPcpJh4xYH4eSToc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}