SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f10ad28b43b36bac5dfcde19535de1bdc932dc2b24792d6710f7b3d9c680fba0' 
  AND token = 's6cRDjOyK9yXAVWGHrpsJ/VPxgEiuZwFNGHu9gXsfIc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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