SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '4774938641a7099e9ddb999054f1a3e78cf74863a74667bdfa7c01a183186fab' 
  AND token = 'oG65+AnfFXEFbDGFqDG7NdISOzVLpCQMOHsfFVAs0bI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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