SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '760a57431b20af406e637d0579b032f0d0d98b139ee569d750c0463cbc34af08' 
  AND token = 'xAjxnk2dv0IzNIDVictTfZZFhryfU2rNMayGgT71jYU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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