SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31d399d8f5011cf3f3de0e5aec7802156ff550f69ac0fbb9b9f7887e7ffcf45c' 
  AND token = 'FqNFbNNnbZffrRnmIyoA47WBQp1FdG/suoHhQplgx1k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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