SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4bcefe790a53c1ea372ccbf173108bf69a6e2d504c0caa7557cfa6e749c79f44' 
  AND token = 'mEBjuWncnPXivEASZMaFpQlh5S0F23QldHPM5VdT3aY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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