SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '784ce98bf7df3c14ee9751de40c9f438df60fcb8cec6d66ea719c28c755ce5d3' 
  AND token = '2CxvO2QaZuRUugB0A/OdFqdGhCQ+km45qTajgW7KgJU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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