SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '741fe0a6294323b23e55a8dc685656393b11c23d154cac9384a03c569cb7f35e' 
  AND token = 'IUF+PKVTvPf+vEWPPGXuY+FWmhs70AqoV7QOM7aw0J0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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