SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '553bbc18cfb7c459bbda23582990a6f8c7a3d0e7e5b8bd7817a1d83de591df27' 
  AND token = 'xJGjMN2cQJOwDgLyCQiaxmF3sLiZPI+q4RGsyS/JUuA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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