SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f17fbdde6dc526a211385552cdbada0141042241668c0d92e2aa3d02bdfe841c' 
  AND token = 'rfT+PpmPkQsgPi8huPVPcRnEFWMd/36aJh0Mmkymi30=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00066

JSON explain

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