SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12b886db7aa8753074c3046bb6e87730381cdf597c97142a44290a2dce4fafa0' 
  AND token = 'dF+Ef73kwnSlzt1avdnILitKtfTKoRl3hALnvl1+Bmo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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