SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7678a1487a4ab70139d91dd0208b671acadfc638c77bfb54372739c67edad6e' 
  AND token = 'PpQcS3p0RF8af46fxPE66sSUh0ebx3FFITJlhoRyOTM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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