SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '450b362593eabee9437472caf3be9073b11b4ffb0164ba7ea85d1e830a589b9b' 
  AND token = 'QemSOWmrhZJRY+lpbtEq6dcajx+qVu36ssQwqopowws=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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