SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '8d5fd5b410071a621216d20fdc0b7b9ed664b5c3c932494d5787c0e2e337f486' 
  AND token = '0VMLYSXNBl5whaUvDCRm6mGPlatQT43QqL3dg3OqfKE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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