SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '899f40c02356bed67c78fbcc950e868a4c956de90b5d87e0143cc40ff4bb191c' 
  AND token = 'aIbhAcwiVCLsqTETZSFDLkz9Z1uk3JnuJMg+nfQvnjg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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