SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a8ef0ae70788f05110bfd07093b713d1c88397026ec18d96b02bcd4a7da6b78' 
  AND token = 'wHYqq9hbXJW/elbogMcL/DhAI0cLG9MbRAvw+I2w6SI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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