SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '836dc594dfca8cdfe07f81cdacf579ca323800e81f9e250624a622120e24c54e' 
  AND token = 'VApQX+6nc+8VSGRrrareybtAnyjVWL7gMi7Elf8wbQo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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