SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb9f04aea9c3ddb2fad29023f1fcdecfb7afac2531116879856728a9710eb37f' 
  AND token = 'ORYnKihQ9acOXgEzegY3iI885Dvrl1f+cESVQ2JUqns=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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