SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5322647d2bafa706efa826c1cb5878ec8af61adebb1031f9db0421019969b87' 
  AND token = 'b6wOrXLDXjdQyZMjjGJO83gG5utGH/yQCY8Q+hP3sLs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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