SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f78eaab3601b577ac8cfeaeb8ac021e41db03717b958c9ee6768c421bdbaa047' 
  AND token = 'MfoUvHXIasQamkcgF/mDXUn3oBSExAe9Thj+HQifrL8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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