SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8973cee5d8db4458661e92f17ef1ec2750952c66a824a527afdffb9933777823' 
  AND token = 'z1QG9chhl9cdqQUeqvGpsrqOWqnoT3ByJvpiqjxlJPo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00010

JSON explain

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