SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '95210200f01b6e5a5ebe3498631d91d45be93b03b912f3f2c477f8bf8f87f50b' 
  AND token = '5np2XXfgVz7J1vx//rJoB/ioGQLFEXLQe+xywnsGQPw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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