SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '90b3bb9f5bce96713f7a1a8d9bf07adbf4f7b56bf61bd9bf0189bd266508463d' 
  AND token = 'FP+nXbfn2UJmZFpKGcxl5+GGLR7Gzy2U4VKvVy9mWis=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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