SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '274be1a21e28599df15986f2c70810075643228a12737b88d9d7304a71e2f0af' 
  AND token = 'QkP1K+pF645zWC467SqwAP/+H+ovViLYEGYebG5eLTs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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