SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '54e83a55649d50d1fcfbb71375d22876a5b9270ee229c0948779f1196f933038' 
  AND token = '1T1omonbpajNCW9kAo0VyJP0ev3lbrTJOAay4rcjKfI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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