SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7c891537199195013657f2f412fa81dff634bdb4573c83e5a6d4d65ec6a3c0bc' 
  AND token = 'SWfbg/9+w1b6zXIMsEXuArqrZHBATbW5qMTkjPgwpgU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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