SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '257b2646c392fa261d655302221c4c535375282b3fa3ce2179fc535fbdd37b83' 
  AND token = 'WHrwLNYSZdB1ul/RZHJX3xFKu+7Vj121+FXX4KMJ+/o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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