SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71223deaf796ce74c04014148ca9729e40f224fc47fafcf6549568fb094c2703' 
  AND token = 'CjtLZJFy52cMkZFA4OrzYc9R48mXbePtguhogy9mwPs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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