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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5b7f8cb4a24c80dbc1e325307d853bc34f70f5519b4623d1994a45cada2ab31b' 
  AND token = 'Pc30jOe5ySUCMiTYxYV3rvhWo5lcRdmJPE2ANQ/zIF4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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