SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c35969269d22135484d09c18611e1739b46936af638bdce7dab6f9053f1ac288' 
  AND token = 'YF8NhB0fczvd6tsRYOZCw9vndaznDgf1DZ2bxVKgUHU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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