SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f703b266a8cd6f0fc93dc760694a192c27f0eb4905477ef55213aac607ac46e4' 
  AND token = 'zwE4bsDeL7AlJGaG2niZEwlLzoYagZDMexhweLVh95c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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