SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87ab49e4cd1f5877d2f4b3a4e5274006cbaf65bd73a13f699f13ea8a9b463597' 
  AND token = '5qiKyn5ZXPyIwOgpOvGZFYcQWZCnXOBuSAcPsR3WNFg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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