SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '756e465dce93a746ee4db8adbb53eacc7450d1045d042e459d1995660384794e' 
  AND token = '6Y+FEfdAqLWZjr2zwdxuPBefSQMjUrMkBExeHh04lcA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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