SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68105ee3df4f08d2a8ad4fdae796428b65b564e852b0904b010fb588058e517c' 
  AND token = 'uZY1fnoH9djHAdBsm2jbbZosJIsxVmtqasAdQLxndk0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}