SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b4e102f50bc2f314498416f6ec7bd213ec1f632c5ad329b492bc0368df185a5a' 
  AND token = 'e6hyxKja1Eah79N3vvff60o0u4f6yHtyof3RJd1qM0Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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