SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '19e4498050c8fe888a06636fd2a07c97462417a4218460b3341177cb6064c339' 
  AND token = 'Pc1q6JMyxIlFw4xtwFFAqke//UsICiWtyaV1+QAM8Eo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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