SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39cb071be8db717880dc5da3589a0d8208d01fd22754dbc3589984a5aa4882e1' 
  AND token = 'fzvaRwU3OW0uVxfbHQCXQTfqyebmtpXZbglAAeIo+8c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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