SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aec5f13847a559a9bd29f7006a791f506c11964d2dd099485333e95081f5a0a2' 
  AND token = 'W7z5nVrS2CnKu0Yh+MQgUgCZftCYdFcG5cEJz8/GmZc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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