SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35b8498d30297a75dbfd89d8d0f3b117ca4f99577afd82cd8eb660d269b3abaa' 
  AND token = 'rbjmwEv+CBCnnJnPAlE4itFROIAgPYh3rtMGRkmqRuY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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