SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '48a2e0f139988d843107699fb951b510945659c0cac15d676d654e880a1fd496' 
  AND token = 'ZKUVLwvY6D5WtkgA9/v5M/h42EJKmn++dAEXVcsfG8g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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