SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd0550e1369437e1e0df0c505207b28c1681b7710f499202324cb835ac0ea1adb' 
  AND token = 'chLJEbGtTLO27A9W9k3jadYAmDytt3DYdl67iMgEr2M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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