SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cca93efc921073f9742143749556126b0c82fb0a3354e9fad667df2d7781f885' 
  AND token = 'rz/k4kDdZ9EglN6ioIiPZ+3En0+IFYqMAuPaqZSansk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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