SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28a0e3f497364030a31af2049607555f8684cc3a5b94173158ff7f2f674a01c9' 
  AND token = 'PlaTsgnAljCuIsuasRQ22NpXg2weOISNfIHqk4bC+1w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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