SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5b034d183b746173e3567d4de6cfb497b70b999bf7ddea06a899861a981c2a4' 
  AND token = 'WOm76EMHUwBIz1KBHWHTcH9XhlXN2CBVbSr0P6zgdmw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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