SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68d9ff57ac1bf0b4102512944aba9452753d00d535d7d8f47afffabf842bda33' 
  AND token = 'evnaNRNnFaDXTQtzTB+IWY1ExSoExiceSqxyJQYFb9s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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