SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3ba07436f98014463e810dcdf43d8d539c1490b12d2c7da53ebce48d2a9aac31' 
  AND token = '5FSa5z4QRSW+TlzuoPIaQvfe2kv1tAisSBWsM2R+ucE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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