SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ea3d89a853327fea46b27678a25233fce7fed6cb08ba6b46af2113239a1656f' 
  AND token = '0fZB2hJtF+SqKannP+ToUOyvHqKGq4CHL2B0UQFliIg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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