SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9e376f817de6da168000d56b3353b3c43832738e8bdbc11ca2adba754fd6742f' 
  AND token = '/vEAovGMYHgaLcSh1jE1xubyKjXqhD5s559T9/zpTbI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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