SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2a4da4ad1a6ebf0e844af7713b6c6a747811583261e04da71fb37715c9693b6d' 
  AND token = '8J//Lo4IF2PihjGfklMi+iugYTTdqzm1euuP7NZATgI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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