SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8fc661f35b6dfcbd9ef9745c1f09a0ab25a0d664ceb2dbf974b89fc759c8d4a' 
  AND token = 'XFwuBzk5I+WWH+v3/Zbs9EBdzqUs2dq/0omYOOjm6ik=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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