SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5cb8ea85e0e8d1c7e5923bfc1d78f8df24cfcbc706e0bfef6043fa10c260849c' 
  AND token = 'FMrbiM6IkfHx6ACmUuHDbabNMQMTszwoGvqACr6Swys=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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