SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '24fff1b0c53da73bda2a4168f6382d60111e4b3d3d1320492c41bc3a8f9fe764' 
  AND token = 'rW1mYtPPj6sxtZqnnlBUf6oXQEpBR5cRQMcJGVw01Ek=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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