SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac6968fe02a15d547d15334b593f0f5df05d92143661e8efea23caaef3ae9a05' 
  AND token = 'XULUbvq5m2CGMxktpjWC4PmZLQpC7NHm4jKeZ0acfOw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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