SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3587fb12e4692ac1e14f0b0813cff1bf2bbb35082552b2ddbcfcc2b9120e064c' 
  AND token = 'w+vvZvhvo6nzTXSp8nj/XgmvbOqboJbQJoxfHtGFJyk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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