SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf393eb647fed6af26d2ce8dceeadeccf9167a0b095beae104fbaba9333b852d' 
  AND token = 'MxJbL7YYIOweg37IrSRLWTQNN4a11LAK7V2ZdcWAmwY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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