SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6ff99de2502daf30d062fc6730aad822bdec980f17ea006ccb4c3733d1dc84e' 
  AND token = 'rrFPtzO523Ypjqe7bSHHs9YBMquhiTkyNFtCiOoDMpc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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