SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1421d5736c0d1918bc731de720e4505f69943302afcab5b51333739778b8a8b7' 
  AND token = 'a3khE70G/wsTgO3gNLJobNNolO8S+mxCu7WFY6oNmQo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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