SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78835c2fc115747e853d7f900b5f824aa16176a66243cafaedd1c5f38071bb9e' 
  AND token = 'teMxCxfjFmr54cNgrxkkBeKEu+7SAg2oYW3B3p0ZoqM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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