SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7e66cb667d5e1c16d7eced1ec234902210df422595042581cc9e044c038a8451' 
  AND token = 'Skx1iZeR+xKiwkR+pRh4kFr1txHMuwhOWnmmGw/qupA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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