SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2a4005ed2caf740b84dd865b127299cf9024e3c89bc7a991ed3398d263c54643' 
  AND token = 'OQi0I/juT3sjBYy+Fxh+UlEwWAWjVWeczm2Ss7De5vE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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